BIO_SC 1010 1st Edition Lecture 19Outline of Last Lecture I. Early LifeII. When and how did Life Begin?III. ProkaryotesIV. Eukaryotes Outline of Current Lecture I. Ecology II. BiosphereIII. Distribution patternsIV. Dispersion patternsV. Population growth Current Lecture• Ecology is the study of organisms in their environment• The study of how organisms interact with each other and with their environment -between organisms-organisms and their nonliving environment• 1958 Isle Royale- Moose and Wolves were observed on the island• 1959- scientists started tracking the separate populations• Ecology can be studied at many levels• It is convenient to divide ecology into five increasingly comprehensive levels• Organismal Ecology-individual: a single organism of a particular species-ex: one wolf-ecologists can study how an individual organism fares in its surroundings• Population Ecology These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-ecologists study a group of individuals• Community Ecology-interacting populations of different species-ex: wolves prey on moose, ticks infest moose, moose feed on trees-ecologists study interacting populations of different species• Ecosystem Ecology-ecologists study all living organisms in an area and the nonliving components of the environment • Scientists monitor populations through field work• Passive sampling monitors population healthBiosphere• The biosphere includes biotic and abiotic factors • The living organisms of an ecosystem constitute its biotic factors• The abiotic factors of an ecosystem are its nonliving components -abiotic factors can have a profound effect on the life within an ecosystem • Biotic refers to the living components of an environment • Abiotic factors like weather and habitat can also influence population size in a density-dependent mannerDistribution Patterns• How organisms are distributed in geographic space-depends on resources • Resources like currency, anything the organism needs to survive: food, shelter, water, etc. are limiting factors • Population density and dispersion are important measurements• Population density is the number of members of a species per unit area or volume of thehabitat• Dispersion patterns are the way individuals are spaced within a habitatDispersion Patterns• Dispersion patterns generally reflect behavioral or ecological adaptations• Allows individuals to maximize their access to resources -ex: moose • A clumped distribution-resources are unevenly distributed-social behavior dictates grouping -ex: wolves• Uniform distribution usually results from territories behavior-uniform resources Population Growth• The growth rate of a population is the difference between the birth rate and the death rate of a given population• Growth models can predict changes in population size• Population size is calculated from the number of births minus the number of deaths• Ecologists have modeled changes in population size • Exponential population growth-imagine a population where there are no predators, no disease, and plenty of food• Exponential growth each new generation is a multiple of the previous generation• Exponential growth requires unlimited resources• Most populations cannot sustain exponential growth indefinitely• Limiting factors: environmental constraints that put a cap on the size of a population• Carrying capacity is the maximum population size that can survive in an environment• The logistic growth model: population grows rapidly until it nears its carrying capacity forthat environment • Logistic growth included limiting factors • Limiting factors include two broad categories• Density-dependent factors are limiting factors whose influence is affected by population density -competition, disease• Density-independent factors are unrelated to population density-weather, environmental disturbance • Human population growth is exponential• Unlike nearly every natural population, humans have demonstrated exponential growth, especially over the last 250 years • Population age structure can inform future population size-current population growth is affected by the birth rate 15 to 30 years ago, since that is when todays child-bearers were